Subject: RE: VS: VS: [Sipping] FW: I-DACTION:draft-sawada-sipping-sip-offeranswer-01.txt (Comments 4 to 6)

From: "Christer Holmberg \(JO/LMF\)" <[email-masked]>
Date: Tue, 27 Jun 2006 09:23:55 +0200

Hi, 

>>>Precisely which scenarios do you mean. It is pretty crazy to expect
>>>such behavior, but I am not too surprised if there are scenarios like

>>>that.
>>>I think there are a cases that require a UAS to be psychic. (Those
>>>related to REFER often feel that way. Dale has recently written 
>>>something on that.)
>> 
>>[CHH] It's quite a while since we discussed this, but hopefully those 
>>who pushed for the specfic behavior can correct me if I'm wrong. The 
>>scenario was something like the following:
>> 
>User A receives an hold re-INVITE. Later (when some transfer functions 
>>have taken place) user A receives an empty re-INVITE. Now, in order to

>>make things work, user A is supposed to un-hold the session and send 
>>an SDP offer as for a new session - not simply return the SDP from the

>>previous offer/answer transaction.
>
>This doesn't require User A to be psychic - only to keep stating its
desires at each opportunity.
>
>In this scenario I believe User A was *put on hold* - he didn't *want*
to be on hold. So at each opportunity (like the offerless reinvite) it
simply 
>states what it wants - which is *not* to be on hold.
>
>If, after A had been put on hold it decided to initiate its own hold
action (perhaps because another call was received), then when the
reinvite is 
>received it might indeed specify SENDONLY. That wouldn't be what the
sender of the reinvite wants to hear, but it is the current situation.
(Of course 
>when A decided to do it own hold it probably should have done its own
reinvite specifying INACTIVE.)

Ok, so what is the "desire" of an MGC (or any other entity without
direct user control)? How does an MGC know whether he "wants" to be on
hold or not?

Regards,

Christer

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---

From: Paul Kyzivat <[email-masked]>
Date: Tue, 27 Jun 2006 09:45:53 -0400

> direct user control)? How does an MGC know whether he "wants" to be on

It needs to figure it out based on interactions with the other side.

For a "regular" UA, I think a reasonable way to make the determination 
is based on whether the media stream(s) are connected to a primary local 
source, sink, or both, or neither. I think the same works for an MGC.

Signaling on the non-sip side might influence this state.

	Paul